パルスオキシメーター(pulse oximeter)
Wiki
プローブを指先や耳などに付けて、侵襲せずに脈拍数と経皮的動脈血酸素飽和度（SpO2）をモニターする医療機器である。モニター結果を内蔵メモリーに記録できるものや腕時計のような小型のものもある。
Organic electronics could lead to cheap, wearable medical sensors
Date:December 10, 2014 sciencedaily.com
Source:University of California - Berkeley
Summary: A pulse oximeter, commonly used to measure heart rate and blood oxygen levels, has been created using all organic materials instead of silicon.
The advance could lead to cheap, flexible sensors that could be used like a Band-Aid.
Future fitness trackers could soon add blood-oxygen levels to the list of vital signs measured with new technology developed by engineers at UC Berkeley.
"There are various pulse oximeters already on the market that measure pulse rate and blood-oxygen saturation levels, but those devices use
rigid conventional electronics, and they are usually fixed to the fingers or earlobe,"
said Ana Arias, an associate professor of electrical engineering and computer sciences and head of the UC Berkeley team that is developing a new organic optoelectronic sensor.
The engineers put the new prototype up against a conventional pulse oximeter and found that the pulse and oxygen readings were just as accurate.
The research team reported its findings in the journal Nature Communications.
Giving silicon a run for its money
A conventional pulse oximeter typically uses light-emitting diodes (LEDs) to send red and infrared light through a fingertip or earlobe. Sensors detect how much light makes it through to the other side.
Bright, oxygen-rich blood absorbs more infrared light, while the darker hues of oxygen-poor blood absorb more red light. The ratio of the two wavelengths reveals how much oxygen is in the blood.
For the organic sensors, Arias and her team of graduate students -- Claire Lochner, Yasser Khan and Adrien Pierre -- used red and green light, which yield comparable differences to red and infrared when it comes to distinguishing high and low levels of oxygen in the blood.
Using a solution-based processing system, the researchers deposited the green and red organic LEDs and the translucent light detectors onto a flexible piece of plastic. By detecting the pattern of fresh arterial blood flow, the device can calculate a pulse.
"We showed that if you take measurements with different wavelengths, it works, and if you use unconventional semiconductors, it works,"
said Arias.
"Because organic electronics are flexible, they can easily conform to
the body."
Arias added that because the components of conventional oximeters are relatively expensive, healthcare providers will choose to disinfect them if they become contaminated. In contrast,
"organic electronics are cheap enough that they are disposable like a Band-Aid after use,"
she said.
Journal Reference:
1.Claire M. Lochner, Yasser Khan, Adrien Pierre, Ana C. Arias. All-organic optoelectronic sensor for pulse oximetry. Nature Communications, 2014; 5: 5745 DOI: 10.1038/ncomms6745
Pulse oximetry is a ubiquitous non-invasive medical sensing method for measuring pulse rate and arterial blood oxygenation.
Conventional pulse oximeters use expensive optoelectronic components that restrict sensing locations to finger tips or ear lobes due to their rigid form and area-scaling complexity.
In this work, we report a pulse oximeter sensor based on organic materials, which are compatible with flexible substrates. Green (532 nm) and red (626 nm) organic light-emitting diodes (OLEDs) are used with an organic photodiode (OPD) sensitive at the aforementioned wavelengths.
The sensor’s active layers are deposited from solution-processed materials via spin-coating and printing techniques.
The all-organic optoelectronic oximeter sensor is interfaced with conventional electronics at 1 kHz and the acquired pulse rate and oxygenation are calibrated and compared with a commercially available oximeter.
The organic sensor accurately measures pulse rate and oxygenation with errors of 1% and 2%, respectively.